NASA has a warning for everyone planning a trip to Mars in the near future – it might be a good idea to wrap yourself in an extra layer of tinfoil when you travel According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high, reaching levels 19 percent higher than observed in the past 50 years and sparking a rethink on the radiation shielding needed for astronauts.